Bleeding mechanism for hydraulic brakes



Nov. 18, 1947. s. SCHNELL 2,430,954A

, l BLEEDING MECHANISM FOR HYDAULZICl BRAKES Filed June 12, 1944 f g sheetssheet 1 57:51@ Saw/MEM Nov. `18, 1947.

s. SCHNELL 2,430,954

V BLEEDING MECHANISM FOR HYDRAULIC BRAKES A Filed June l2', 1944 2 Sheets-Sheet 2 FIGA.1

INVENTOR. 1/ 30M/Q4 ArraPA/fy Patented Nov. 18, 1947 BLEEDING MECHANISM FOR HYDRAULIC BRAKES f Steve Schnell, Kirkwood, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application June 12, 1944, sel-iai No. 539,857V

4 claims. (el. cog- 7545 This invention is directed to brake controls and in its more specific aspects is concerned with a means and mechanism for controlling the bleeding of air from the pressure fluid line from a station or position remote from the brake cylinder. I

An object of this invention is to produce a bleeding mechanism for pressure fluid brakes of the hydraulic type controllable from a position remote from the brake cylinder.

Another object of the invention is to provide a manually controlled bleeding means for hydraulic brakes4 operable from a station remote from the brake cylinder.

A further object of the invention is to pro.- vide a bleeder means for a hydraulically operated brake mechanism in which the bleeding is controlled from a station adjacent the master cylinder device.

A still further object of the invention is to provide in a hydraulic brake, a bleeder means electrically controlled in which the control switch is located at the operators station for the brake. Y

A still further object of the invention is to provide a mechanism in a hydraulically operated brake wherein `a solenoid operated valve controlled from a station adjacent the master cylinder device is employed `to bleed any entrapped air from the brake system.

Another and still further object of the invention is to provide a substantially closed pressure fluid system for a hydraulic brake in which air and fluid bledrfrom the brake cylinder is directed to an elevated reservoir.

Another and still further object of the invention is to provide in a hydraulic brake, a conduit system in which air is bled from the brake cylinder by a manually controlled means operable'from a station adjacent the master cylinder and in which fluid in the brake system is continuously circulated and returned to an elevated supply tank.

Another and still further object of the invention is to provide a remotely controlled bleeder valve in a hydraulic brake in which the fluid and entrapped air released from the brake cylinder is led to an elevated supply tank.

A still further object of the invention is to provide a hydraulic brake lsystem in which the 2 operating portion thereof is maintained continuously filled with liquid. Y

Other and further objects of the invention will occur to those skilled in the arts to which this application pertains as the description proceeds, which, taken in connection with the accompanying drawings, set fortha preferred embodiment of the invention and selected modicatic-ns thereof `but such disclosures are not to be construed as a limitation of the invention which is limited only by the appended claims and any and all modifications, alterations and variations of structure coming Within the spirit andscope thereof are deemed to be included herein.

` In the drawings:

Figure 1 shows a preferred embodiment of the invention; y

Figure 2 shows a longitudinal section View of the bleedervalve;

Figure 3 shows a modified control circuit for the bleeder valve; and `Figure 4` shows a longitudinal section View of the bleeder `valve and its operating solenoid.

YHydraulic brakes frequently have entrapped air in the pressure fluid lines leading to and in the brake cylinder that renders the operation thereof erratic and uncertain in character. Various devices have been developed to bleed such entrapped air from the conduits leading to the brake cylinder and from the brake cylinder and conduits connected thereto. Each of such devices is generally characterized by the fact that an operator or attendant must operate such bleeding devices right at the brake cylinder itself and further mfust provide an auxiliary vessel in order to collect any liquid which may escape along with the entrapped air. The most ideal operating condition for hydraulic brakes occurs when there is a line of hydraulic fluid between the` master cylinder andthe brake cylinder to thereby render the brake cylinder immediately responsive to any changes in the operating conditions imposed by the master cylinder. If the `bleeder Valves arranged on the brake cylinder must be opened at or near the cylinder, such operation is frequently delayed because of the difficulty in obtaining access to the brake cylinders. Applicants invention eliminates the necessity of removing any operating mechanism on or adjacent to the brake device to bleed entrapped air from the brake operating system and is constructed and arranged such that the bleeding of air from the system may take place from the control station adjacent to the master cylinder operating the brake. Additionally, an auxiliary supply vessel for fluid is provided in an elevated position above the brake cylinder and any liquid and air exhausted from the brake cylinder and attached conduit is led to the elevated supply in order that the air may be eliminated at this point and any liquid carried along with the released air is collected inthe elevated vessel. The invention provides a simple, ei-

cient and effective means controlled from the brake operator station whereby entrapped air` is bled from the pressure fluid brake operatingV mechanism.

rIhe objects and advantages set forth above' are obtained in the system disclosed in Figure 1 in which I is a master cylinder of conventional design, whose internal construction may be'of theY master cylinder is ledv by means ofl conduit I` to one side ofthe brake cylinder 5- of the brake mechanism 6; Brake mechanism 6 comprises a rotatable element or drum 'lf' that is fixed to an appropriatel rotatable element on a traveling crane, portable hoist or other vehicle as the case may be. The brake 5 is normallyv released and is ret'ai'nedl in released position by means of springs 8-8. Lever 9 upon upward movement normally urges theshoe elements IIl-I pivoted to a base II into engagement with drum 'I. This movement occurs when pressure fluid isadmitted to brake cylinder 5 whereupon thel springs are placed in tension and the brake shoes I-`--II) are applied to the druml I to stop-rotation of said drum. The brake drum is conventional in character and is well knownto the arts.

Pressure fluid is exhausted from the brake cylinder 5` by conduit |22? that leads toa bleeder valve I3. Conduit I4 connects totheV exhaust side of bleeder valve |13l and leads to ay tank or sump I5, which vessel is preferably positioned above the level of bra-ke cylinder 5 and master cylinder I. Conduit I6' is ledfrom tank I'5 and suppliespressure fluid'v toa reservoir (not shown) provided in master cylinder deviceV I. The foregoing constitutes a substantially closed hydraulic circuit through which the pressure fluid may be circulated uponV eachI actuation; of the bleeder valve i3 and at no time after the opening of the bleeder valve I3 .is it strictly necessary that the pressure fluid flow back to the master cylinder device through conduit 4'.

Bleeder valve I3 is actuated by a solenoid I1 to which conductors I3 and' I-9` are connected and in one of which a manually controlled switch 2i) is arranged. Conductors I-8 and I9 lead to a suitable source of supply for thel energization of the solenoid II`.

When the operator actuates the foot pedal 2 and discovers that there is entrapped air in conduit l and brake cylinder device 5V, he closes switch 2D, thereby energizing solenoid I'I whose armature 2| engages a plunger 22 in bleeder Valve I3 to thereby open and said valve and allow any entrapped air contained in conduit 4 and brake cylinder 5 plus any liquid contained therein to escape to conduit I4 exhausting into tank I5 returning the air to the atmosphere and any uid therein to said tank I5. Valve I3 is held open until the operator is certain a solid line of liquid is in the brake cylinder and conduits connected thereto.

The detailed construction of bleeder valve I3 is shown in Figure 2 in which a housing 23 preferably of circular form yis provided having a reduced threaded end 2li that is adapted to be turned into one of the exhaust ports of brake cylinder 5 or may be threaded to a length of conduit I2 as illustrated in Figure 1. Within housing 313 a sealing cup 25, preferably formed from some highly resilient material of rubberlike characteristic, is arranged and held in said housing 23 by means of a retaining plug 26. The sealing cup 25 at its center is formed into a Valve seat 2l engageable by the valve element Ztl'andA a' light spring 29 normally urges the valve Y 28 into engagement with seat 2'I and also assists y into the bore in plug 30.

in maintaining the valve in its central position.

Threaded into plug 26 is another plug 3E! that is counterbored and in said counterbore, plunger Z2 is slidably arranged. In the larger diameter ofthe counterbore, an enlargement 3| is provided. on said plunger 22 and beyondenlarge mentSI, the plunger has anextension 32 of reduced diameter that extends to a point adjacent the valve ZS. The reduced diameter extension 32 ofi the plunger `is supported-y inthe bore of plug. 33 by means of another bored plug 33, plug 33 being rigidly held in the larger bore of plug 3U. A. spring 34' isl disposed above the reduced diameter portion 32' of the plunger betweenthe enlargement 3| and plug 33 and urgesthe said plunger to the left as showny in Figure 2. A sealing element 35 yis disposed about plunger 22. between the enlargement 3| and the end of the plugin order to prevent the escape of pressurefluid about said plunger 22.

Thetting 36 arranged about plug 30 connects with conduit I il as illustrated and at its other end is connectable to the bore in housing 23. The fitting. 35 isv apertured to` receive said plug 3).l and. the plug 3i] is provided with a plurality of apertures 31 that lead to a groove 38 formed in the exterior of plug 39 in order that pressure fluid may be easily conducted from the bore in plugV 3U' to the bore in tting 36. Plug 33 is appropriately apertured as at 39 in order to conduct the pressure fluid? through said plug 33 and The foregoing structure provides the necessary passageways for the transmission of pressure fluid. Suitable gaskets are provided between the fitting and plug and between the plug 26 and housing 23 to eliminate any possibility of leakage of pressure fluid at those points.

The operationl of the foregoing structure is thought to be clear but briey consists of forcing the pressure fluid generated by the master cylinder device I to and through conduit 4 to the brake cylinder 5. Since valve 28 is maintained normally closed', the pressure fluid thus generated is appliedl to the brake cylinder to release the brake shoes from the brake drum 1. If any entrapped air is present in conduit 4 of brake cylinder 5, it is exhausted from the system by energizing the solenoid IIl upon closure of switch 2li located adjacent the master cylinder device I. Theenergization of solenoid- I'I causes its plunger 2i` to engageplunger 22 urging the same toward the right against the tension of spring 34 such that the reduced endV 32 of the plunger engages valve 28 liftingitfrom seat 27 andallowing fluid tovescape around the valve 28 into the bore of 'plug 26V through-apertures 39, the bore in plug 35, apertures 3'! and thence through theA bore in fitting 3G through conduit I4 and into the elevated tank or sump'i5. Upon release or opening 'of switch 25, the solenoid is cle-energized and spring34 will restore plunger 22'to the position indicated and spring 29 will again reseat valve 28 on seat 2'I of cup element 25 whose normal function is to prevent the escape of pressure fluid and hold .the same within the bore provided in housing 23; If, after master cylinder I is inoperative, should a vacuum be created in brake cylinder 5, gravitational action will urge liquid in conduit I4 to open valve 28, allowing liquid to re-enter brake cylinder 5, thereby maintaining said system full of liquid.

In the selected modicatio-n of the above described mechanism set forth in Figures 3 and 4, the basic elements of master cylinder I, foot pedal 2 on spindle 3, conduit 4, brake cylinder device 5, conduit l4, and tank or sump I function in exactly the same manner as set forth above and the same reference numerals apply to each of these parts.

The control circuit for the bleeder Valve is difierently arranged in the modification and comprises the power line 40 leading to a source of supply line 4l, the latter of which is connected to a contact 42 fixed in the pad 2a on foot pedal 2. A pivoted contact supporting lever 43 having a contact 44 fixed thereon is supported on spindle 45 and is maintained in a condition such that the contacts 42 and 44 remain out of engagement. A conductor 46 connects contact 44 with one side of a switch 4l and the other side of switch 4l by means of conductor 48 leads to an appropriate power source.

Bleeder valve 49 is connected between conduit I4 and brake cylinder 5 by means of conduit I2 or it may be directly connected to the brake cylinder, comprising initially a housing 5!) internally threaded at its reduced end to receive conduit i2 and is provided with another interiorly threaded extension 5I into which conduit I4 is threaded. The housing 50 is provided with a double counterbore 52 into one side of which the conduit I2 is secured and in the other side of which the spring 53 is arranged such that it engages with a valve seat element 54 provided with a sealing cup 55, the valve seat 54 being slidable in the bore of housing 50.

Threaded into an enlarged extension of housing 53 is a fitting 55 in which is arranged a counterbored element 5l, one end of which fits into one of the counterbores in housing 50 and having a reduced end 53 enga-ging with the valve seat 54. Within the counterbore of tting 56, the valve element 59 is sli'dably received and is rigidly secured to a plunger element 60 operable by solenoid coil 6I. Spring c2 is arranged in the larger of the counterbores in fitting 56 and engages with solenoid plunger 5E! to open bleeder valve 49 upon de-energization of coil 6I. The valve seat 54 and valve 55 are appropriately seated and shaped to provide a Huid-tight connection therebetween and sealing cup 55 is normally intended to prevent the escape of pressure uid from the bore provided in housing 50. rIhe reduced end 58 of fitting 55 is appropriately apertured in order that pressure fluid may pass from the bore in housing 53 toward the conduit I4. Suitable provision is madefor `the insulation of plunger V6I) from coil ,6I and gasket elements are provided inthe Valve assembly Wherever the possibility of leakage of pressure fluid may occur.

In the operation of this device the operator places his foot upon the element 43 and pivots it `about spindle 45 to bring elements 44 and 42 into contact, thereby closing the circuit to coil 6I and simultaneously operating master cylinder I. The energization of coil 6I causes plunger 60 to advance and closes bleeder valve 49 by having the valve element 59. rmly engaged with valve seat 54. In the event VVthat air is entrapped in brake cylinder 5 orv conduits V4 and I2, switch 41 is opened, thereby opening the circuit to coil 6I deenergizing the same such that spring 62 may open the valve 49 and allow any entrapped air to pass through valve 49 and accompanying liquid through conduit I4 into elevated tank or source I5 allowing the air to escape to atmosphere. During any period of inaction valve 49 is open and should any vacuum be developed in brake cylinder 5, liquid from sump I5 will ow from sump or tank I5 to ll conduit I4, valve 49, conduit I2, brake cylinder 5 and any space in conduit 4 to maintain a solid line of liquid between the master cylinder and brake cylinder 5.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a brake system, a master cylinder, a brake cylinder, and a sump, said sump positioned above said brake cylinder; a bleeder valve to remove entrapped air from said brake cylinder; a solenoid to operate said bleeder valve; means to control the energization of said solenoid to open and close said bleeder valve including a switch disposed adjacent said master cylinder to enable the operator to control said valve from the position remote therefrom; and a switch associated with said master cylinder to le-energize said solenoid when said master cylinder is not operating.

2. In a brake system, a master cylinder, a brake cylinder, and a sump serially connected; a bleeder valve connected between said sump and said brake cylinder; a solenoid to control said valve; a switch associated with said master cylinder; a circuit including said switch to control said solenoid, said circuit closable upon actuation of said master cylinder to thereby close said bleeder valve; and another switch openable to deenergize said coil and enable said bleeder valve to bleed entrapped air and other iiuid from said brake cylinder to said sump.

3. In a brake control system, the combination of a brake cylinder; a master cylinder; a liquid reservoir; means to serially connect each of said devices into a substantially closed hydraulic circuit; a bleeder valve in said circuit so connected as to exhaust entrapped air into said reservoir; electrically operated means for operating said bleeder valve; and a circuit for said electrically operated means which includes a normally closed manual switch and a normally open switch closable when said master cylinder is operated.

4. In a brake control system, the combination of a, master cylinder having an operating pedal pivoted thereto; a brake cylinder; a liquid reservoir; means to connect each of said devices into a substantially closed hydraulic circuit; a bleeder valve in said circuit arranged such that it is enabled to exhaust entrapped air and other fluid in said brake cylinder into said liquid reservoir; a solenoid to operate said bleeder valve; and a circuit for said solenoid which includes a normally closed .manually Aoperated switch .and a .normally open -switch on. Lsaid --pedal Aclosable when said pedal -is depressed.

REFERENCES l01211131) "The -following references 4'stre of record inthe .le of this patent:

UNITED STATES PATENTS 1,230,150 Geraghty :June l19, 1917 Number Number 'Name Date Pieper Apr. 16, 1929 ,Loughead May 13, 1930 Banas Dec. 25, 1934 Messier Sept. 10, 1935 Cox Oct. 20, 1936 Loweke Dec. .26, 1939 Stelzer Jan. 2, 1940 Johnson May 23, 1944 FOREIGN PATENTS Country Date Great Britain July 5, 1934 

